Horton had the mole removed Thursday after the fan contacted the team doctor prompting him to get it checked.

Horton took to social media to thank the anonymous fan.    

"Shout out to the person that emailed the swim team doctor and told me to get my mole checked out. Good call. Very good call," Horton wrote wearing a bandage in the photograph.

Horton made headlines at Rio earlier this year following comments he made about 400m swimmer Sun Yang.

"I don’t have time or respect for drug cheats", Horton said of the Chinese swimmer who tested positive to a stimulant in 2014.

"I used the word 'drug cheat' because he tested positive.

"I just have a problem with him testing positive and still competing."

Horton subsequently became enemy number one of Chinese swim fans.